Inline melt control via RF power

ABSTRACT

Various embodiments provide apparatus and methods for melting materials and for containing the molten materials within melt zone during melting. Exemplary apparatus may include a vessel configured to receive a material for melting therein; a load induction coil positioned adjacent to the vessel to melt the material therein; and a containment induction coil positioned in line with the load induction coil. The material in the vessel can be heated by operating the load induction coil at a first RF frequency to form a molten material. The containment induction coil can be operated at a second RF frequency to contain the molten material within the load induction coil. Once the desired temperature is achieved and maintained for the molten material, operation of the containment induction coil can be stopped and the molten material can be ejected from the vessel into a mold through an ejection path.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional application of U.S. application Ser.No. 13/651,654 filed Oct. 15, 2012, now pending, which is consideredpart of and is incorporated by reference in its entirety in thedisclosure of this application.

FIELD

The present disclosure is generally related to apparatus and methods formelting materials and for containing the molten materials within meltzone during melting.

BACKGROUND

Some injection molding machines use an induction coil to melt materialbefore injecting the material into a mold. However, in horizontallydisposed machines where the material is melted in a vessel positionedfor horizontal ejection, magnetic fluxes from the induction coil tend tocause the melt to move unpredictably, e.g., to flow towards and/or outof the melt zone, which can make it difficult to control the uniformityand temperature of the melt.

Current solutions for melting in vessels designed for horizontalejection include use of a gate that is in contact with the melt andphysically blocks the melt from flowing (horizontally) out of theinduction coil in the melt zone. Problems arise, however, due to gateconfigurations, wherein the gate is a point of contact with the melt andimpurities may be introduced by the gate. In addition, the gateconfiguration may reduce the space available for the melt zone becausethe gate must be actuated up and down in order to allow the melt toflow. Further, the melt may undesirably flow towards and/or out of thehorizontal ejection path of the vessel due to challenge of the timingcontrol as when to raise the gate during the injection process of themelt. Furthermore, the gate is potentially a consumable part and needsto be replaced after a certain number of uses.

It is desirable to contain the melt in the melt zone of horizontallydesigned systems at desired high temperatures when it is heated ormelted, but without introducing a gate to physically block the melt.

SUMMARY

A proposed solution according to embodiments herein for meltingmaterials (e.g., metals or metal alloys) in a vessel is to contain themelt or molten material within melt zone.

In accordance with various embodiments, there is provided an apparatus.The apparatus may include a vessel configured to receive a material formelting therein; a load induction coil positioned adjacent to the vesselto melt the material therein; and a containment induction coilpositioned in line with the load induction coil. The containmentinduction coil is configured to contain the melt within the loadinduction coil.

In accordance with various embodiments, there is provided a meltingmethod using an apparatus. The apparatus may include a vessel configuredto receive a material for melting therein; a load induction coilpositioned adjacent to the vessel to melt the material therein; and acontainment induction coil positioned in line with the load inductioncoil. The material in the vessel can be heated by operating the loadinduction coil at a first RF frequency to form a molten material. Whileheating, the containment induction coil can be operated at a second RFfrequency to contain the molten material within the load induction coil.

In accordance with various embodiments, there is provided a meltingmethod using an apparatus. The apparatus may include a vessel configuredto receive a material for melting therein; a load induction coilpositioned adjacent to the vessel to melt the material therein; and acontainment induction coil positioned in line with the load inductioncoil. The material in the vessel can be heated by operating the loadinduction coil at a first RF frequency to form a molten material. Whileheating, the containment induction coil can be operated at a second RFfrequency to contain the molten material within the load induction coil.Once the desired temperature is achieved and maintained for the moltenmaterial, operation of the containment induction coil can be stopped andthe molten material can be ejected from the vessel into a mold throughan ejection path.

Also, in accordance with an embodiment, the material for meltingcomprises a BMG feedstock, and a BMG part may be formed.

Further, in an embodiment, the first induction coil and the secondinduction coil are part of the same coil, wherein they are connected toeach other electrically but configured in an array such that anon-uniform magnetic field is produced. In another embodiment, the firstand the second induction coils are part of the same coil and associatedwith an electrical tap that allow independent control of either or bothcoils, i.e., control of at least one portion or one side of the singlecoil, so that the magnetic field can be changed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A provides a temperature-viscosity diagram of an exemplary bulksolidifying amorphous alloy.

FIG. 1B provides a schematic of a time-temperature-transformation (TTT)diagram for an exemplary bulk solidifying amorphous alloy.

FIGS. 2A to 2D show various exemplary embodiments of the arrangements ofthe first induction coil and a second induction, for melting andcontainment of a material.

FIG. 3 shows a schematic diagram of an exemplary injection moldingsystem/apparatus in accordance with various embodiments of the presentteachings.

FIG. 4 depicts an injection molding system configured having aninduction coil.

FIG. 5 depicts another exemplary injection molding system/apparatus inaccordance with various embodiments of the present teachings.

FIG. 6 depicts a method for melting/molding a material in accordancewith various embodiments of the present teachings.

DETAILED DESCRIPTION

All publications, patents, and patent applications cited in thisSpecification are hereby incorporated by reference in their entirety.

The articles “a” and “an” are used herein to refer to one or to morethan one (i.e., to at least one) of the grammatical object of thearticle. By way of example, “a polymer resin” means one polymer resin ormore than one polymer resin. Any ranges cited herein are inclusive. Theterms “substantially” and “about” used throughout this Specification areused to describe and account for small fluctuations. For example, theycan refer to less than or equal to ±5%, such as less than or equal to±2%, such as less than or equal to ±1%, such as less than or equal to±0.5%, such as less than or equal to ±0.2%, such as less than or equalto ±0.1%, such as less than or equal to ±0.05%.

Bulk-solidifying amorphous alloys, or bulk metallic glasses (“BMG”), area recently developed class of metallic materials. These alloys may besolidified and cooled at relatively slow rates, and they retain theamorphous, non-crystalline (i.e., glassy) state at room temperature.Amorphous alloys have many superior properties than their crystallinecounterparts. However, if the cooling rate is not sufficiently high,crystals may form inside the alloy during cooling, so that the benefitsof the amorphous state can be lost. For example, one challenge with thefabrication of bulk amorphous alloy parts is partial crystallization ofthe parts due to either slow cooling or impurities in the raw alloymaterial. As a high degree of amorphicity (and, conversely, a low degreeof crystallinity) is desirable in BMG parts, there is a need to developmethods for casting BMG parts having controlled amount of amorphicity.

FIG. 1A (obtained from U.S. Pat. No. 7,575,040) shows aviscosity-temperature graph of an exemplary bulk solidifying amorphousalloy, from the VIT-001 series of Zr—Ti—Ni—Cu—Be family manufactured byLiquidmetal Technology. It should be noted that there is no clearliquid/solid transformation for a bulk solidifying amorphous metalduring the formation of an amorphous solid. The molten alloy becomesmore and more viscous with increasing undercooling until it approachessolid form around the glass transition temperature. Accordingly, thetemperature of solidification front for bulk solidifying amorphousalloys can be around glass transition temperature, where the alloy willpractically act as a solid for the purposes of pulling out the quenchedamorphous sheet product.

FIG. 1B (obtained from U.S. Pat. No. 7,575,040) shows thetime-temperature-transformation (TTT) cooling curve of an exemplary bulksolidifying amorphous alloy, or TTT diagram. Bulk-solidifying amorphousmetals do not experience a liquid/solid crystallization transformationupon cooling, as with conventional metals. Instead, the highly fluid,non crystalline form of the metal found at high temperatures (near a“melting temperature” Tm) becomes more viscous as the temperature isreduced (near to the glass transition temperature Tg), eventually takingon the outward physical properties of a conventional solid.

Even though there is no liquid/crystallization transformation for a bulksolidifying amorphous metal, a “melting temperature” Tm may be definedas the thermodynamic liquidus temperature of the correspondingcrystalline phase. Under this regime, the viscosity of bulk-solidifyingamorphous alloys at the melting temperature could lie in the range ofabout 0.1 poise to about 10,000 poise, and even sometimes under 0.01poise. A lower viscosity at the “melting temperature” would providefaster and complete filling of intricate portions of the shell/mold witha bulk solidifying amorphous metal for forming the BMG parts.Furthermore, the cooling rate of the molten metal to form a BMG part hasto such that the time-temperature profile during cooling does nottraverse through the nose-shaped region bounding the crystallized regionin the TTT diagram of FIG. 1B. In FIG. 1B, Tnose is the criticalcrystallization temperature Tx where crystallization is most rapid andoccurs in the shortest time scale.

The supercooled liquid region, the temperature region between Tg and Txis a manifestation of the extraordinary stability againstcrystallization of bulk solidification alloys. In this temperatureregion the bulk solidifying alloy can exist as a high viscous liquid.The viscosity of the bulk solidifying alloy in the supercooled liquidregion can vary between 10¹² Pa s at the glass transition temperaturedown to 10⁵ Pa s at the crystallization temperature, the hightemperature limit of the supercooled liquid region. Liquids with suchviscosities can undergo substantial plastic strain under an appliedpressure. The embodiments herein make use of the large plasticformability in the supercooled liquid region as a forming and separatingmethod.

One needs to clarify something about Tx. Technically, the nose-shapedcurve shown in the TTT diagram describes Tx as a function of temperatureand time. Thus, regardless of the trajectory that one takes whileheating or cooling a metal alloy, when one hits the TTT curve, one hasreached Tx. In FIG. 1B, Tx is shown as a dashed line as Tx can vary fromclose to Tm to close to Tg.

The schematic TTT diagram of FIG. 1B shows processing methods of diecasting from at or above Tm to below Tg without the time-temperaturetrajectory (shown as (1) as an example trajectory) hitting the TTTcurve. During die casting, the forming takes place substantiallysimultaneously with fast cooling to avoid the trajectory hitting the TTTcurve. The processing methods for superplastic forming (SPF) from at orbelow Tg to below Tm without the time-temperature trajectory (shown as(2), (3) and (4) as example trajectories) hitting the TTT curve. In SPF,the amorphous BMG is reheated into the supercooled liquid region wherethe available processing window could be much larger than die casting,resulting in better controllability of the process. The SPF process doesnot require fast cooling to avoid crystallization during cooling. Also,as shown by example trajectories (2), (3) and (4), the SPF can becarried out with the highest temperature during SPF being above Tnose orbelow Tnose, up to about Tm. If one heats up a piece of amorphous alloybut manages to avoid hitting the TTT curve, you have heated “between Tgand Tm”, but one would have not reached Tx.

Typical differential scanning calorimeter (DSC) heating curves ofbulk-solidifying amorphous alloys taken at a heating rate of 20 C/mindescribe, for the most part, a particular trajectory across the TTT datawhere one would likely see a Tg at a certain temperature, a Tx when theDSC heating ramp crosses the TTT crystallization onset, and eventuallymelting peaks when the same trajectory crosses the temperature range formelting. If one heats a bulk-solidifying amorphous alloy at a rapidheating rate as shown by the ramp up portion of trajectories (2), (3)and (4) in FIG. 1B, then one could avoid the TTT curve entirely, and theDSC data would show a glass transition but no Tx upon heating. Anotherway to think about it is trajectories (2), (3) and (4) can fall anywherein temperature between the nose of the TTT curve (and even above it) andthe Tg line, as long as it does not hit the crystallization curve. Thatjust means that the horizontal plateau in trajectories might get muchshorter as one increases the processing temperature.

Phase

The term “phase” herein can refer to one that can be found in athermodynamic phase diagram. A phase is a region of space (e.g., athermodynamic system) throughout which all physical properties of amaterial are essentially uniform. Examples of physical propertiesinclude density, index of refraction, chemical composition and latticeperiodicity. A simple description of a phase is a region of materialthat is chemically uniform, physically distinct, and/or mechanicallyseparable. For example, in a system consisting of ice and water in aglass jar, the ice cubes are one phase, the water is a second phase, andthe humid air over the water is a third phase. The glass of the jar isanother separate phase. A phase can refer to a solid solution, which canbe a binary, tertiary, quaternary, or more, solution, or a compound,such as an intermetallic compound. As another example, an amorphousphase is distinct from a crystalline phase.

Metal, Transition Metal, and Non-Metal

The term “metal” refers to an electropositive chemical element. The term“element” in this Specification refers generally to an element that canbe found in a Periodic Table. Physically, a metal atom in the groundstate contains a partially filled band with an empty state close to anoccupied state. The term “transition metal” is any of the metallicelements within Groups 3 to 12 in the Periodic Table that have anincomplete inner electron shell and that serve as transitional linksbetween the most and the least electropositive in a series of elements.Transition metals are characterized by multiple valences, coloredcompounds, and the ability to form stable complex ions. The term“nonmetal” refers to a chemical element that does not have the capacityto lose electrons and form a positive ion.

Depending on the application, any suitable nonmetal elements, or theircombinations, can be used. The alloy (or “alloy composition”) caninclude multiple nonmetal elements, such as at least two, at leastthree, at least four, or more, nonmetal elements. A nonmetal element canbe any element that is found in Groups 13-17 in the Periodic Table. Forexample, a nonmetal element can be any one of F, Cl, Br, I, At, O, S,Se, Te, Po, N, P, As, Sb, Bi, C, Si, Ge, Sn, Pb, and B. Occasionally, anonmetal element can also refer to certain metalloids (e.g., B, Si, Ge,As, Sb, Te, and Po) in Groups 13-17. In one embodiment, the nonmetalelements can include B, Si, C, P, or combinations thereof. Accordingly,for example, the alloy can include a boride, a carbide, or both.

A transition metal element can be any of scandium, titanium, vanadium,chromium, manganese, iron, cobalt, nickel, copper, zinc, yttrium,zirconium, niobium, molybdenum, technetium, ruthenium, rhodium,palladium, silver, cadmium, hafnium, tantalum, tungsten, rhenium,osmium, iridium, platinum, gold, mercury, rutherfordium, dubnium,seaborgium, bohrium, hassium, meitnerium, ununnilium, unununium, andununbium. In one embodiment, a BMG containing a transition metal elementcan have at least one of Sc, Y, La, Ac, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo,W, Mn, Tc, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd,and Hg. Depending on the application, any suitable transitional metalelements, or their combinations, can be used. The alloy composition caninclude multiple transitional metal elements, such as at least two, atleast three, at least four, or more, transitional metal elements.

The presently described alloy or alloy “sample” or “specimen” alloy canhave any shape or size. For example, the alloy can have a shape of aparticulate, which can have a shape such as spherical, ellipsoid,wire-like, rod-like, sheet-like, flake-like, or an irregular shape. Theparticulate can have any size. For example, it can have an averagediameter of between about 1 micron and about 100 microns, such asbetween about 5 microns and about 80 microns, such as between about 10microns and about 60 microns, such as between about 15 microns and about50 microns, such as between about 15 microns and about 45 microns, suchas between about 20 microns and about 40 microns, such as between about25 microns and about 35 microns. For example, in one embodiment, theaverage diameter of the particulate is between about 25 microns andabout 44 microns. In some embodiments, smaller particulates, such asthose in the nanometer range, or larger particulates, such as thosebigger than 100 microns, can be used.

The alloy sample or specimen can also be of a much larger dimension. Forexample, it can be a bulk structural component, such as an ingot,housing/casing of an electronic device or even a portion of a structuralcomponent that has dimensions in the millimeter, centimeter, or meterrange.

Solid Solution

The term “solid solution” refers to a solid form of a solution. The term“solution” refers to a mixture of two or more substances, which may besolids, liquids, gases, or a combination of these. The mixture can behomogeneous or heterogeneous. The term “mixture” is a composition of twoor more substances that are combined with each other and are generallycapable of being separated. Generally, the two or more substances arenot chemically combined with each other.

Alloy

In some embodiments, the alloy composition described herein can be fullyalloyed. In one embodiment, an “alloy” refers to a homogeneous mixtureor solid solution of two or more metals, the atoms of one replacing oroccupying interstitial positions between the atoms of the other; forexample, brass is an alloy of zinc and copper. An alloy, in contrast toa composite, can refer to a partial or complete solid solution of one ormore elements in a metal matrix, such as one or more compounds in ametallic matrix. The term alloy herein can refer to both a completesolid solution alloy that can give single solid phase microstructure anda partial solution that can give two or more phases. An alloycomposition described herein can refer to one comprising an alloy or onecomprising an alloy-containing composite.

Thus, a fully alloyed alloy can have a homogenous distribution of theconstituents, be it a solid solution phase, a compound phase, or both.The term “fully alloyed” used herein can account for minor variationswithin the error tolerance. For example, it can refer to at least 90%alloyed, such as at least 95% alloyed, such as at least 99% alloyed,such as at least 99.5% alloyed, such as at least 99.9% alloyed. Thepercentage herein can refer to either volume percent or weightpercentage, depending on the context. These percentages can be balancedby impurities, which can be in terms of composition or phases that arenot a part of the alloy.

Amorphous or Non-Crystalline Solid

An “amorphous” or “non-crystalline solid” is a solid that lacks latticeperiodicity, which is characteristic of a crystal. As used herein, an“amorphous solid” includes “glass” which is an amorphous solid thatsoftens and transforms into a liquid-like state upon heating through theglass transition. Generally, amorphous materials lack the long-rangeorder characteristic of a crystal, though they can possess someshort-range order at the atomic length scale due to the nature ofchemical bonding. The distinction between amorphous solids andcrystalline solids can be made based on lattice periodicity asdetermined by structural characterization techniques such as x-raydiffraction and transmission electron microscopy.

The terms “order” and “disorder” designate the presence or absence ofsome symmetry or correlation in a many-particle system. The terms“long-range order” and “short-range order” distinguish order inmaterials based on length scales.

The strictest form of order in a solid is lattice periodicity: a certainpattern (the arrangement of atoms in a unit cell) is repeated again andagain to form a translationally invariant tiling of space. This is thedefining property of a crystal. Possible symmetries have been classifiedin 14 Bravais lattices and 230 space groups.

Lattice periodicity implies long-range order. If only one unit cell isknown, then by virtue of the translational symmetry it is possible toaccurately predict all atomic positions at arbitrary distances. Theconverse is generally true, except, for example, in quasi-crystals thathave perfectly deterministic tilings but do not possess latticeperiodicity.

Long-range order characterizes physical systems in which remote portionsof the same sample exhibit correlated behavior. This can be expressed asa correlation function, namely the spin-spin correlation function:G(x,x′)=

s(x),s(x′)

.

In the above function, s is the spin quantum number and x is thedistance function within the particular system. This function is equalto unity when x=x′ and decreases as the distance |x−x′| increases.Typically, it decays exponentially to zero at large distances, and thesystem is considered to be disordered. If, however, the correlationfunction decays to a constant value at large |x−x′|, then the system canbe said to possess long-range order. If it decays to zero as a power ofthe distance, then it can be called quasi-long-range order. Note thatwhat constitutes a large value of |x−x′| is relative.

A system can be said to present quenched disorder when some parametersdefining its behavior are random variables that do not evolve with time(i.e., they are quenched or frozen)—e.g., spin glasses. It is oppositeto annealed disorder, where the random variables are allowed to evolvethemselves. Embodiments herein include systems comprising quencheddisorder.

The alloy described herein can be crystalline, partially crystalline,amorphous, or substantially amorphous. For example, the alloysample/specimen can include at least some crystallinity, withgrains/crystals having sizes in the nanometer and/or micrometer ranges.Alternatively, the alloy can be substantially amorphous, such as fullyamorphous. In one embodiment, the alloy composition is at leastsubstantially not amorphous, such as being substantially crystalline,such as being entirely crystalline.

In one embodiment, the presence of a crystal or a plurality of crystalsin an otherwise amorphous alloy can be construed as a “crystallinephase” therein. The degree of crystallinity (or “crystallinity” forshort in some embodiments) of an alloy can refer to the amount of thecrystalline phase present in the alloy. The degree can refer to, forexample, a fraction of crystals present in the alloy. The fraction canrefer to volume fraction or weight fraction, depending on the context. Ameasure of how “amorphous” an amorphous alloy is can be amorphicity.Amorphicity can be measured in terms of a degree of crystallinity. Forexample, in one embodiment, an alloy having a low degree ofcrystallinity can be said to have a high degree of amorphicity. In oneembodiment, for example, an alloy having 60 vol % crystalline phase canhave a 40 vol % amorphous phase.

Amorphous Alloy or Amorphous Metal

An “amorphous alloy” is an alloy having an amorphous content of morethan 50% by volume, preferably more than 90% by volume of amorphouscontent, more preferably more than 95% by volume of amorphous content,and most preferably more than 99% to almost 100% by volume of amorphouscontent. Note that, as described above, an alloy high in amorphicity isequivalently low in degree of crystallinity. An “amorphous metal” is anamorphous metal material with a disordered atomic-scale structure. Incontrast to most metals, which are crystalline and therefore have ahighly ordered arrangement of atoms, amorphous alloys arenon-crystalline. Materials in which such a disordered structure isproduced directly from the liquid state during cooling are sometimesreferred to as “glasses.” Accordingly, amorphous metals are commonlyreferred to as “metallic glasses” or “glassy metals.” In one embodiment,a bulk metallic glass (“BMG”) can refer to an alloy, of which themicrostructure is at least partially amorphous. However, there areseveral ways besides extremely rapid cooling to produce amorphousmetals, including physical vapor deposition, solid-state reaction, ionirradiation, melt spinning, and mechanical alloying. Amorphous alloyscan be a single class of materials, regardless of how they are prepared.

Amorphous metals can be produced through a variety of quick-coolingmethods. For instance, amorphous metals can be produced by sputteringmolten metal onto a spinning metal disk. The rapid cooling, on the orderof millions of degrees a second, can be too fast for crystals to form,and the material is thus “locked in” a glassy state. Also, amorphousmetals/alloys can be produced with critical cooling rates low enough toallow formation of amorphous structures in thick layers—e.g., bulkmetallic glasses.

The terms “bulk metallic glass” (“BMG”), bulk amorphous alloy (“BAA”),and bulk solidifying amorphous alloy are used interchangeably herein.They refer to amorphous alloys having the smallest dimension at least inthe millimeter range. For example, the dimension can be at least about0.5 mm, such as at least about 1 mm, such as at least about 2 mm, suchas at least about 4 mm, such as at least about 5 mm, such as at leastabout 6 mm, such as at least about 8 mm, such as at least about 10 mm,such as at least about 12 mm. Depending on the geometry, the dimensioncan refer to the diameter, radius, thickness, width, length, etc. A BMGcan also be a metallic glass having at least one dimension in thecentimeter range, such as at least about 1.0 cm, such as at least about2.0 cm, such as at least about 5.0 cm, such as at least about 10.0 cm.In some embodiments, a BMG can have at least one dimension at least inthe meter range. A BMG can take any of the shapes or forms describedabove, as related to a metallic glass. Accordingly, a BMG describedherein in some embodiments can be different from a thin film made by aconventional deposition technique in one important aspect—the former canbe of a much larger dimension than the latter.

Amorphous metals can be an alloy rather than a pure metal. The alloysmay contain atoms of significantly different sizes, leading to low freevolume (and therefore having viscosity up to orders of magnitude higherthan other metals and alloys) in a molten state. The viscosity preventsthe atoms from moving enough to form an ordered lattice. The materialstructure may result in low shrinkage during cooling and resistance toplastic deformation. The absence of grain boundaries, the weak spots ofcrystalline materials in some cases, may, for example, lead to betterresistance to wear and corrosion. In one embodiment, amorphous metals,while technically glasses, may also be much tougher and less brittlethan oxide glasses and ceramics.

Thermal conductivity of amorphous materials may be lower than that oftheir crystalline counterparts. To achieve formation of an amorphousstructure even during slower cooling, the alloy may be made of three ormore components, leading to complex crystal units with higher potentialenergy and lower probability of formation. The formation of amorphousalloy can depend on several factors: the composition of the componentsof the alloy; the atomic radius of the components (preferably with asignificant difference of over 12% to achieve high packing density andlow free volume); and the negative heat of mixing the combination ofcomponents, inhibiting crystal nucleation and prolonging the time themolten metal stays in a supercooled state. However, as the formation ofan amorphous alloy is based on many different variables, it can bedifficult to make a prior determination of whether an alloy compositionwould form an amorphous alloy.

Amorphous alloys, for example, of boron, silicon, phosphorus, and otherglass formers with magnetic metals (iron, cobalt, nickel) may bemagnetic, with low coercivity and high electrical resistance. The highresistance leads to low losses by eddy currents when subjected toalternating magnetic fields, a property useful, for example, astransformer magnetic cores.

Amorphous alloys may have a variety of potentially useful properties. Inparticular, they tend to be stronger than crystalline alloys of similarchemical composition, and they can sustain larger reversible (“elastic”)deformations than crystalline alloys. Amorphous metals derive theirstrength directly from their non-crystalline structure, which can havenone of the defects (such as dislocations) that limit the strength ofcrystalline alloys. For example, one modern amorphous metal, known asVitreloy™, has a tensile strength that is almost twice that ofhigh-grade titanium. In some embodiments, metallic glasses at roomtemperature are not ductile and tend to fail suddenly when loaded intension, which limits the material applicability in reliability-criticalapplications, as the impending failure is not evident. Therefore, toovercome this challenge, metal matrix composite materials having ametallic glass matrix containing dendritic particles or fibers of aductile crystalline metal can be used. Alternatively, a BMG low inelement(s) that tend to cause embitterment (e.g., Ni) can be used. Forexample, a Ni-free BMG can be used to improve the ductility of the BMG.

Another useful property of bulk amorphous alloys is that they can betrue glasses; in other words, they can soften and flow upon heating.This can allow for easy processing, such as by injection molding, inmuch the same way as polymers. As a result, amorphous alloys can be usedfor making sports equipment, medical devices, electronic components andequipment, and thin films. Thin films of amorphous metals can bedeposited as protective coatings via a high velocity oxygen fueltechnique.

A material can have an amorphous phase, a crystalline phase, or both.The amorphous and crystalline phases can have the same chemicalcomposition and differ only in the microstructure—i.e., one amorphousand the other crystalline. Microstructure in one embodiment refers tothe structure of a material as revealed by a microscope at 25×magnification or higher. Alternatively, the two phases can havedifferent chemical compositions and microstructures. For example, acomposition can be partially amorphous, substantially amorphous, orcompletely amorphous.

As described above, the degree of amorphicity (and conversely the degreeof crystallinity) can be measured by fraction of crystals present in thealloy. The degree can refer to volume fraction of weight fraction of thecrystalline phase present in the alloy. A partially amorphouscomposition can refer to a composition of at least about 5 vol % ofwhich is of an amorphous phase, such as at least about 10 vol %, such asat least about 20 vol %, such as at least about 40 vol %, such as atleast about 60 vol %, such as at least about 80 vol %, such as at leastabout 90 vol %. The terms “substantially” and “about” have been definedelsewhere in this application. Accordingly, a composition that is atleast substantially amorphous can refer to one of which at least about90 vol % is amorphous, such as at least about 95 vol %, such as at leastabout 98 vol %, such as at least about 99 vol %, such as at least about99.5 vol %, such as at least about 99.8 vol %, such as at least about99.9 vol %. In one embodiment, a substantially amorphous composition canhave some incidental, insignificant amount of crystalline phase presenttherein.

In one embodiment, an amorphous alloy composition can be homogeneouswith respect to the amorphous phase. A substance that is uniform incomposition is homogeneous. This is in contrast to a substance that isheterogeneous. The term “composition” refers to the chemical compositionand/or microstructure in the substance. A substance is homogeneous whena volume of the substance is divided in half and both halves havesubstantially the same composition. For example, a particulatesuspension is homogeneous when a volume of the particulate suspension isdivided in half and both halves have substantially the same volume ofparticles. However, it might be possible to see the individual particlesunder a microscope. Another example of a homogeneous substance is airwhere different ingredients therein are equally suspended, though theparticles, gases and liquids in air can be analyzed separately orseparated from air.

A composition that is homogeneous with respect to an amorphous alloy canrefer to one having an amorphous phase substantially uniformlydistributed throughout its microstructure. In other words, thecomposition macroscopically includes a substantially uniformlydistributed amorphous alloy throughout the composition. In analternative embodiment, the composition can be of a composite, having anamorphous phase having therein a non-amorphous phase. The non-amorphousphase can be a crystal or a plurality of crystals. The crystals can bein the form of particulates of any shape, such as spherical, ellipsoid,wire-like, rod-like, sheet-like, flake-like, or an irregular shape. Inone embodiment, it can have a dendritic form. For example, an at leastpartially amorphous composite composition can have a crystalline phasein the shape of dendrites dispersed in an amorphous phase matrix; thedispersion can be uniform or non-uniform, and the amorphous phase andthe crystalline phase can have the same or a different chemicalcomposition. In one embodiment, they have substantially the samechemical composition. In another embodiment, the crystalline phase canbe more ductile than the BMG phase.

The methods described herein can be applicable to any type of amorphousalloy. Similarly, the amorphous alloy described herein as a constituentof a composition or article can be of any type. The amorphous alloy caninclude the element Zr, Hf, Ti, Cu, Ni, Pt, Pd, Fe, Mg, Au, La, Ag, Al,Mo, Nb, Be, or combinations thereof. Namely, the alloy can include anycombination of these elements in its chemical formula or chemicalcomposition. The elements can be present at different weight or volumepercentages. For example, an iron “based” alloy can refer to an alloyhaving a non-insignificant weight percentage of iron present therein,the weight percent can be, for example, at least about 20 wt %, such asat least about 40 wt %, such as at least about 50 wt %, such as at leastabout 60 wt %, such as at least about 80 wt %. Alternatively, in oneembodiment, the above-described percentages can be volume percentages,instead of weight percentages. Accordingly, an amorphous alloy can bezirconium-based, titanium-based, platinum-based, palladium-based,gold-based, silver-based, copper-based, iron-based, nickel-based,aluminum-based, molybdenum-based, and the like. The alloy can also befree of any of the aforementioned elements to suit a particular purpose.For example, in some embodiments, the alloy, or the compositionincluding the alloy, can be substantially free of nickel, aluminum,titanium, beryllium, or combinations thereof. In one embodiment, thealloy or the composite is completely free of nickel, aluminum, titanium,beryllium, or combinations thereof.

For example, the amorphous alloy can have the formula (Zr, Ti)_(a)(Ni,Cu, Fe)_(b)(Be, Al, Si, B)_(c), wherein a, b, and c each represents aweight or atomic percentage. In one embodiment, a is in the range offrom 30 to 75, b is in the range of from 5 to 60, and c is in the rangeof from 0 to 50 in atomic percentages. Alternatively, the amorphousalloy can have the formula (Zr, Ti)_(a)(Ni, Cu)_(b)(Be)_(c), wherein a,b, and c each represents a weight or atomic percentage. In oneembodiment, a is in the range of from 40 to 75, b is in the range offrom 5 to 50, and c is in the range of from 5 to 50 in atomicpercentages. The alloy can also have the formula (Zr, Ti)_(a)(Ni,Cu)_(b)(Be)_(c), wherein a, b, and c each represents a weight or atomicpercentage. In one embodiment, a is in the range of from 45 to 65, b isin the range of from 7.5 to 35, and c is in the range of from 10 to 37.5in atomic percentages. Alternatively, the alloy can have the formula(Zr)_(a)(Nb, Ti)_(b)(Ni, Cu)_(c)(Al)_(d), wherein a, b, c, and d eachrepresents a weight or atomic percentage. In one embodiment, a is in therange of from 45 to 65, b is in the range of from 0 to 10, c is in therange of from 20 to 40 and d is in the range of from 7.5 to 15 in atomicpercentages. One exemplary embodiment of the aforedescribed alloy systemis a Zr—Ti—Ni—Cu—Be based amorphous alloy under the trade nameVitreloy™, such as Vitreloy-1 and Vitreloy-101, as fabricated byLiquidmetal Technologies, CA, USA. Some examples of amorphous alloys ofthe different systems are provided in Table 1 and Table 2.

TABLE 1 Exemplary amorphous alloy compositions Alloy Atm % Atm % Atm %Atm % Atm % Atm % Atm % Atm % 1 Fe Mo Ni Cr P C B 68.00% 5.00% 5.00%2.00% 12.50% 5.00% 2.50% 2 Fe Mo Ni Cr P C B Si 68.00% 5.00% 5.00% 2.00%11.00% 5.00% 2.50% 1.50% 3 Pd Cu Co P 44.48% 32.35%  4.05% 19.11%  4 PdAg Si P 77.50% 6.00% 9.00% 7.50% 5 Pd Ag Si P Ge 79.00% 3.50% 9.50%6.00%  2.00% 6 Pt Cu Ag P B Si 74.70% 1.50% 0.30% 18.0%  4.00% 1.50%

TABLE 2 Additional Exemplary amorphous alloy compositions (atomic %)Alloy Atm % Atm % Atm % Atm % Atm % Atm % 1 Zr Ti Cu Ni Be 41.20% 13.80%12.50%  10.00% 22.50% 2 Zr Ti Cu Ni Be 44.00% 11.00% 10.00%  10.00%25.00% 3 Zr Ti Cu Ni Nb Be 56.25% 11.25% 6.88%  5.63%  7.50% 12.50% 4 ZrTi Cu Ni Al Be 64.75%  5.60% 14.90%  11.15%  2.60%  1.00% 5 Zr Ti Cu NiAl 52.50%  5.00% 17.90%  14.60% 10.00% 6 Zr Nb Cu Ni Al 57.00%  5.00%15.40%  12.60% 10.00% 7 Zr Cu Ni Al 50.75% 36.23% 4.03%  9.00% 8 Zr TiCu Ni Be 46.75%  8.25% 7.50% 10.00% 27.50% 9 Zr Ti Ni Be 21.67% 43.33%7.50% 27.50% 10 Zr Ti Cu Be 35.00% 30.00% 7.50% 27.50% 11 Zr Ti Co Be35.00% 30.00% 6.00% 29.00% 12 Zr Ti Fe Be 35.00% 30.00% 2.00% 33.00% 13Au Ag Pd Cu Si 49.00%  5.50% 2.30% 26.90% 16.30% 14 Au Ag Pd Cu Si50.90%  3.00% 2.30% 27.80% 16.00% 15 Pt Cu Ni P 57.50% 14.70% 5.30%22.50% 16 Zr Ti Nb Cu Be 36.60% 31.40% 7.00%  5.90% 19.10% 17 Zr Ti NbCu Be 38.30% 32.90% 7.30%  6.20% 15.30% 18 Zr Ti Nb Cu Be 39.60% 33.90%7.60%  6.40% 12.50% 19 Cu Ti Zr Ni 47.00% 34.00% 11.00%   8.00% 20 Zr CoAl 55.00% 25.00% 20.00% 

Other exemplary ferrous metal-based alloys include compositions such asthose disclosed in U.S. Patent Application Publication Nos. 2007/0079907and 2008/0305387. These compositions include the Fe(Mn, Co, Ni, Cu) (C,Si, B, P, Al) system, wherein the Fe content is from 60 to 75 atomicpercentage, the total of (Mn, Co, Ni, Cu) is in the range of from 5 to25 atomic percentage, and the total of (C, Si, B, P, Al) is in the rangeof from 8 to 20 atomic percentage, as well as the exemplary compositionFe48Cr15Mo14Y2C15B6. They also include the alloy systems described byFe—Cr—Mo—(Y,Ln)-C—B, Co—Cr—Mo-Ln-C—B, Fe—Mn—Cr—Mo—(Y,Ln)-C—B, (Fe, Cr,Co)—(Mo,Mn)—(C,B)—Y, Fe—(Co,Ni)—(Zr,Nb,Ta)—(Mo,W)—B,Fe—(Al,Ga)—(P,C,B,Si,Ge), Fe—(Co, Cr,Mo,Ga,Sb)—P—B—C, (Fe, Co)—B—Si—Nballoys, and Fe—(Cr—Mo)—(C,B)—Tm, where Ln denotes a lanthanide elementand Tm denotes a transition metal element. Furthermore, the amorphousalloy can also be one of the exemplary compositions Fe80P12.5C5B2.5,Fe80P11C5B2.5Si1.5, Fe74.5Mo5.5P12.5C5B2.5, Fe74.5Mo5.5P11C5B2.5Si1.5,Fe70Mo5Ni5P12.5C5B2.5, Fe70Mo5Ni5P11C5B2.5Si1.5,Fe68Mo5Ni5Cr2P12.5C5B2.5, and Fe68Mo5Ni5Cr2P11C5B2.5Si1.5, described inU.S. Patent Application Publication No. 2010/0300148.

The amorphous alloys can also be ferrous alloys, such as (Fe, Ni, Co)based alloys. Examples of such compositions are disclosed in U.S. Pat.Nos. 6,325,868; 5,288,344; 5,368,659; 5,618,359; and 5,735,975, Inoue etal., Appl. Phys. Lett., Volume 71, p 464 (1997), Shen et al., Mater.Trans., JIM, Volume 42, p 2136 (2001), and Japanese Patent ApplicationNo. 200126277 (Pub. No. 2001303218 A). One exemplary composition isFe₇₂Al₅Ga₂P₁₁C₆B₄. Another example is Fe₇₂Al₇Zr₁₀Mo₅W₂B₁₅. Anotheriron-based alloy system that can be used in the coating herein isdisclosed in U.S. Patent Application Publication No. 2010/0084052,wherein the amorphous metal contains, for example, manganese (1 to 3atomic %), yttrium (0.1 to 10 atomic %), and silicon (0.3 to 3.1 atomic%) in the range of composition given in parentheses; and that containsthe following elements in the specified range of composition given inparentheses: chromium (15 to 20 atomic %), molybdenum (2 to 15 atomic%), tungsten (1 to 3 atomic %), boron (5 to 16 atomic %), carbon (3 to16 atomic %), and the balance iron.

The amorphous alloy can also be one of the Pt- or Pd-based alloysdescribed by U.S. Patent Application Publication Nos. 2008/0135136,2009/0162629, and 2010/0230012. Exemplary compositions includePd44.48Cu32.35Cu4.05P19.11, Pd77.5Ag6Si9P7.5, andPt74.7Cul.5Ag0.3P18B4Si1.5.

The aforedescribed amorphous alloy systems can further includeadditional elements, such as additional transition metal elements,including Nb, Cr, V, and Co. The additional elements can be present atless than or equal to about 30 wt %, such as less than or equal to about20 wt %, such as less than or equal to about 10 wt %, such as less thanor equal to about 5 wt %. In one embodiment, the additional, optionalelement is at least one of cobalt, manganese, zirconium, tantalum,niobium, tungsten, yttrium, titanium, vanadium and hafnium to formcarbides and further improve wear and corrosion resistance. Furtheroptional elements may include phosphorous, germanium and arsenic,totaling up to about 2%, and preferably less than 1%, to reduce meltingpoint. Otherwise incidental impurities should be less than about 2% andpreferably 0.5%.

In some embodiments, a composition having an amorphous alloy can includea small amount of impurities. The impurity elements can be intentionallyadded to modify the properties of the composition, such as improving themechanical properties (e.g., hardness, strength, fracture mechanism,etc.) and/or improving the corrosion resistance. Alternatively, theimpurities can be present as inevitable, incidental impurities, such asthose obtained as a byproduct of processing and manufacturing. Theimpurities can be less than or equal to about 10 wt %, such as about 5wt %, such as about 2 wt %, such as about 1 wt %, such as about 0.5 wt%, such as about 0.1 wt %. In some embodiments, these percentages can bevolume percentages instead of weight percentages. In one embodiment, thealloy sample/composition consists essentially of the amorphous alloy(with only a small incidental amount of impurities). In anotherembodiment, the composition includes the amorphous alloy (with noobservable trace of impurities).

In one embodiment, the final parts exceeded the critical castingthickness of the bulk solidifying amorphous alloys.

In embodiments herein, the existence of a supercooled liquid region inwhich the bulk-solidifying amorphous alloy can exist as a high viscousliquid allows for superplastic forming. Large plastic deformations canbe obtained. The ability to undergo large plastic deformation in thesupercooled liquid region is used for the forming and/or cuttingprocess. As oppose to solids, the liquid bulk solidifying alloy deformslocally which drastically lowers the required energy for cutting andforming. The ease of cutting and forming depends on the temperature ofthe alloy, the mold, and the cutting tool. As higher is the temperature,the lower is the viscosity, and consequently easier is the cutting andforming.

Embodiments herein can utilize a thermoplastic-forming process withamorphous alloys carried out between Tg and Tx, for example. Herein, Txand Tg are determined from standard DSC measurements at typical heatingrates (e.g. 20° C./min) as the onset of crystallization temperature andthe onset of glass transition temperature.

The amorphous alloy components can have the critical casting thicknessand the final part can have thickness that is thicker than the criticalcasting thickness. Moreover, the time and temperature of the heating andshaping operation is selected such that the elastic strain limit of theamorphous alloy could be substantially preserved to be not less than1.0%, and preferably not being less than 1.5%. In the context of theembodiments herein, temperatures around glass transition means theforming temperatures can be below glass transition, at or around glasstransition, and above glass transition temperature, but preferably attemperatures below the crystallization temperature T_(x). The coolingstep is carried out at rates similar to the heating rates at the heatingstep, and preferably at rates greater than the heating rates at theheating step. The cooling step is also achieved preferably while theforming and shaping loads are still maintained.

Electronic Devices

The embodiments herein can be valuable in the fabrication of electronicdevices using a BMG. An electronic device herein can refer to anyelectronic device known in the art. For example, it can be a telephone,such as a cell phone, and a land-line phone, or any communicationdevice, such as a smart phone, including, for example an iPhone™, and anelectronic email sending/receiving device. It can be a part of adisplay, such as a digital display, a TV monitor, an electronic-bookreader, a portable web-browser (e.g., iPad™), and a computer monitor. Itcan also be an entertainment device, including a portable DVD player,conventional DVD player, Blu-Ray disk player, video game console, musicplayer, such as a portable music player (e.g., iPod™), etc. It can alsobe a part of a device that provides control, such as controlling thestreaming of images, videos, sounds (e.g., Apple TV™), or it can be aremote control for an electronic device. It can be a part of a computeror its accessories, such as the hard drive tower housing or casing,laptop housing, laptop keyboard, laptop track pad, desktop keyboard,mouse, and speaker. The article can also be applied to a device such asa watch or a clock.

A proposed solution according to embodiments herein for meltingmaterials (e.g., metals or metal alloys) in a vessel is to contain themelt or molten material within melt zone.

Embodiments relate to apparatus and methods to control the position andshape of molten feedstock in an inline melting apparatus, a coiloperating at a lower frequency than the main helical melt coil andpositioned near the end of the melt coil is used to exert a force onmolten alloy contained within the latter. The Laplace forces generatedby the “containment” coil act against those generated by the melt coil(which tend to push the alloy out) without substantially reducing theinductive heating of the alloy. This allows the alloy to be melted andcontrollably introduced into another system such as a cold chamber diecaster for subsequent forming. The advantages of the apparatus andmethod would be to allow the alloy to be electromagnetically containedwithout using a physical obstruction to contain the alloy.

FIGS. 2A to 2D shows various embodiments of the apparatus. The apparatuscould comprise a vessel configured to receive a material such as aningot shown in FIGS. 2A to 2D for melting therein. Shown in theembodiments are a first induction coil, configured to melt the materialtherein; and a second induction coil, positioned in line with the firstinduction coil, wherein the second induction coil or a combination ofthe first induction coil and the second induction coil is configured tofunction as a gate or a valve for containing movement of the moltenmaterial in a horizontal direction within the vessel. In one embodiment,the first induction coil is a load or heating coil and the secondinduction coil is a containing coil. Alternatively, in anotherembodiment, the first induction coil is a containing coil and the secondinduction coil is a heating coil. The heating induction coil can be usedto tune the frequency to maximize thermal energy generation on ameltable material (e.g., in the form of an ingot). The containinginduction coil can be used to tune the frequency to maximize forcesapplied to the melt.

For explanatory purposes only, it should be understood that FIGS. 2A-2Dreference injection of molten material into a mold in a horizontaldirection, out of a vessel, from right to left. Accordingly, in theseillustrative embodiments, first induction coil is a heating coil andsecond induction coil is a containing coil. However, the direction ofmovement and the heating/containing coil assignments are not meant to belimiting.

In any of these embodiments, the material for melting could comprise aBMG feedstock, and the apparatus is configured to mold the material intoa BMG part.

In two exemplary embodiments, the first induction coil and the secondinduction coil are part of a single induction coil (shown in FIG. 2B) ortwo distinct induction coils (shown in FIG. 2A). The coils are used tocontrol the melt via RF power. For example, the second coil (e.g.,containment coil) may be provided on the left and the first coil (e.g.,heating coil) on the right. They can be connected and configured tooperate at the same frequency. Accordingly, FIG. 2B shows a coilconfiguration that performs both heating and containment functions. Inoperation, the melt temperature and stifling remains relatively uniformin the region between the first and second coils.

The frequencies of the first and second induction coils may bedifferent. If using a single coil to perform both functions, i.e.,heating and containing, then only one frequency may run. This results ina selected frequency that is a compromise between the frequencies forheating the material and for optimizing force applied to the melt. Inaccordance with an embodiment, the first induction coil and the secondinduction coil are part of a single induction coil having an electricaltap (shown in FIG. 2C) therein configured to independently control thefirst induction coil and the second induction coil. The electrical tapallows independent control of either or both coils, so that the magneticfield can be rapidly changed. In an embodiment wherein a first andsecond induction coil are part of a single coil, the electrical tap canallow control of at least one portion or one side of the single coil.

Optionally, one or both of the first induction coil and the secondinduction coil could comprise a taper shape or cylindrical shape inFIGS. 2A-2D.

The second induction coil could be wrapped around the first inductioncoil as or vice-versa as shown in FIG. 2D. FIG. 2D shows one example, inaccordance with an embodiment, of de-coupling the first (e.g., heating)and second (e.g., containing) induction coils, where the second coiluses similar principles described above. The first and second inductioncoils may have different frequencies. For example, the second inductioncoil could generally have a lower RF frequency than the first inductioncoil.

Also, during melting of meltable material, it is also envisioned that aplunger of the system (e.g., plunger rod 330 of system 300) may beconfigured to assist in containing the meltable material within avessel. For example, in an embodiment wherein a plunger is configured tomove in a horizontal direction from right to left to inject the materialinto a mold (thus ejecting the molten material from the vessel), theplunger may be positioned to contain a melt from a right side (adjacentto first induction coil) to keep molten material from being ejected outthe wrong side. The coil configuration may be designed to contain themelt on the opposite side leading to the mold (left side). In anembodiment, the plunger may be used in with and/or in addition to any ofthe coil configurations shown in FIG. 2A, 2B, 2C, or 2D.

In an embodiment, the meltable material is contained on its bottom by awater-cooled boat, vessel, or container, that may or may not comprisewith a substantially U-shaped channel.

The vessel (not shown in FIGS. 2A to 2D, but instead an ingot within thevessel is shown) could be positioned along a horizontal axis of thefirst induction coil or the second induction such that movement of thematerial in the vessel is in a horizontal direction along an ejectionpath of the vessel. The second induction coil could be positioned nearan ejection end of the vessel, for example, shown in FIG. 2B.

The apparatus could further comprise an additional induction coillocated at either an ejection end of the vessel or an opposite side ofthe ejection end of the vessel. An additional induction coil is notshown in FIGS. 2A to 2D. The vessel could further comprise one or moretemperature regulating channels (not shown in FIGS. 2A to 2D) configuredto flow a fluid therein for regulating a temperature of the vesselduring melting of the material. The apparatus further comprise a mold(not shown in FIGS. 2A to 2D) configured to receive the melt from thevessel and to mold the melt into the BMG part. In FIGS. 2A to 2D, thesecond induction coil or the combination of the first induction coil andthe second induction coil is configured to function as a valve tocontrol movement of the melt from the vessel through an injection pathto the mold (not shown in FIGS. 2A to 2D).

In accordance with various embodiments, there is provided an apparatus.The apparatus may include a vessel configured to receive a material formelting therein; a load induction coil positioned adjacent to the vesselto melt the material therein; and a containment induction coilpositioned in line with the load induction coil. The containmentinduction coil is configured to contain the melt within the loadinduction coil.

In accordance with various embodiments, there is provided a meltingmethod using an apparatus. The apparatus may include a vessel configuredto receive a material for melting therein; a load induction coilpositioned adjacent to the vessel to melt the material therein; and acontainment induction coil positioned in line with the load inductioncoil. The material in the vessel can be heated by operating the loadinduction coil at a first RF frequency to form a molten material. Whilethe melt is heated and/or maintained at desired temperature, thecontainment induction coil can be operated at a second RF frequency tocontain the molten material within the load induction coil.

In accordance with various embodiments, there is provided a meltingmethod using an apparatus. The apparatus may include a vessel configuredto receive a material for melting therein; a load induction coilpositioned adjacent to the vessel to melt the material therein; and acontainment induction coil positioned in line with the load inductioncoil. The material in the vessel can be heated by operating the loadinduction coil at a first RF frequency to form a molten material. Whileheating, the containment induction coil can be operated at a second RFfrequency to contain the molten material within the load induction coil.Once the desired temperature is achieved and maintained for the moltenmaterial, operation of the containment induction coil can be stopped andthe molten material can be ejected from the vessel into a mold throughan ejection path.

The methods, techniques, and devices illustrated herein are not intendedto be limited to the illustrated embodiments. As disclosed herein, anapparatus or a system (or a device or a machine) is configured toperform melting of and injection molding of material(s) (such asamorphous alloys). The apparatus is configured to process such materialsor alloys by melting at higher melting temperatures before injecting themolten material into a mold for molding. As further described below,parts of the apparatus are positioned in-line with each other. Inaccordance with some embodiments, parts of the apparatus (or accessthereto) are aligned on a horizontal axis. The following embodiments arefor illustrative purposes only and are not meant to be limiting.

FIG. 3 illustrates a schematic diagram of such an exemplary apparatus.More specifically, FIG. 3 illustrates an injection molding apparatus300. In accordance with an embodiment, injection molding system 300 caninclude a melt zone 310 configured to melt meltable material 305received therein, and at least one plunger rod 330 configured to ejectmolten material 305 from melt zone 310 and into a mold 340. In anembodiment, at least plunger rod 330 and melt zone 310 are providedin-line and on a horizontal axis (e.g., X axis), such that plunger rod330 is moved in a horizontal direction (e.g., along the X-axis)substantially through melt zone 310 to move the molten material 305 intomold 340. The mold can be positioned adjacent to the melt zone.

The meltable material can be received in the melt zone in any number offorms. For example, the meltable material may be provided into melt zone310 in the form of an ingot (solid state), a semi-solid state, a slurrythat is preheated, powder, pellets, etc. In some embodiments, a loadingport (such as the illustrated example of an ingot loading port 318) maybe provided as part of injection molding apparatus 300. Loading port 318can be a separate opening or area that is provided within the machine atany number of places. In an embodiment, loading port 318 may be apathway through one or more parts of the machine. For example, thematerial (e.g., ingot) may be inserted in a horizontal direction intothe vessel 312 by plunger 330, or may be inserted in a horizontaldirection from the mold side of the injection apparatus 300 (e.g.,through mold 340 and/or through a transfer sleeve 350 into vessel 312).In other embodiments, the meltable material can be provided into meltzone 310 in other manners and/or using other devices (e.g., through anopposite end of the injection apparatus).

Melt zone 310 includes a melting mechanism configured to receivemeltable material and to hold the material as it is heated to a moltenstate. The melting mechanism may be in the form of a vessel 312, forexample, that has a body for receiving meltable material and configuredto melt the material therein. A vessel as used throughout thisdisclosure is a container made of a material employed for heatingsubstances to high temperatures. For example, in an embodiment, thevessel may be a crucible, such as a boat style crucible, or a skullcrucible. In an embodiment, vessel 312 is a cold hearth melting devicethat is configured to be utilized for meltable material(s) while under avacuum (e.g., applied by a vacuum device or pump at a vacuum port 332).In one embodiment, described further below, the vessel is a temperatureregulated vessel.

Vessel 312 may also have an inlet for inputting material (e.g.,feedstock) into a receiving or melting portion 314 of its body. In theembodiments shown in the Figures, the body of vessel 312 may include asubstantially U-shaped structure. However, this illustrated shape is notmeant to be limiting. Vessel 312 can include any number of shapes orconfigurations. The body of the vessel has a length and can extend in alongitudinal and horizontal direction, such that molten material isremoved horizontally therefrom using plunger 330. For example, the bodymay include a base with side walls extending vertically therefrom. Thematerial for heating or melting may be received in a melting portion 314of the vessel. Melting portion 314 is configured to receive meltablematerial to be melted therein. For example, melting portion 314 has asurface for receiving material. Vessel 312 may receive material (e.g.,in the form of an ingot) in its melting portion 314 using one or moredevices of an injection apparatus for delivery (e.g., loading port andplunger).

In an embodiment, body and/or its melting portion 314 may includesubstantially rounded and/or smooth surfaces. For example, a surface ofmelting portion 314 may be formed in an arc shape. However, the shapeand/or surfaces of the body are not meant to be limiting. The body maybe an integral structure, or formed from separate parts that are joinedor machined together. The body of vessel 312 may be formed from anynumber of materials (e.g., copper, silver), include one or morecoatings, and/or configurations or designs. For example, one or moresurfaces may have recesses or grooves therein.

The body of vessel 312 may be configured to receive the plunger rodthere-through in a horizontal direction to move the molten material.That is, in an embodiment, the melting mechanism is on the same axis asthe plunger rod, and the body can be configured and/or sized to receiveat least part of the plunger rod. Thus, plunger rod 330 can beconfigured to move molten material (after heating/melting) from thevessel by moving substantially through vessel 312, and into mold 340.Referencing the illustrated embodiment of apparatus 300 in FIG. 3, forexample, plunger rod 330 would move in a horizontal direction from theright towards the left, through vessel 312, moving and pushing themolten material towards and into mold 340.

To heat melt zone 310 and melt the meltable material received in vessel312, injection apparatus 300 also includes a heat source that is used toheat and melt the meltable material.

At least melting portion 314 of the vessel, if not substantially theentire body itself, is configured to be heated such that the materialreceived therein is melted. Heating is accomplished using, for example,an induction source 320L positioned within melt zone 310 that isconfigured to melt the meltable material. In an embodiment, inductionsource 320L is positioned adjacent vessel 312. For example, inductionsource 320L may be in the form of a coil positioned in a helical patternsubstantially around a length of the vessel body. Accordingly, vessel312 may be configured to inductively melt a meltable material (e.g., aninserted ingot) within melting portion 314 by supplying power toinduction source/coil 320L, using a power supply or source 325. Thus,the melt zone 310 can include an induction zone. Induction coil 320L isconfigured to heat up and melt any material that is contained by vessel312 without melting and wetting vessel 312. Induction coil 320L emitsradiofrequency (RF) waves towards vessel 312. As shown, the body andcoil 320L surrounding vessel 312 may be configured to be positioned in ahorizontal direction along a horizontal axis (e.g., X axis).

In one embodiment, the vessel 312 is a temperature regulated vessel.Such a vessel may include one or more temperature regulating channelsconfigured to flow a gas or a liquid (e.g., water, oil, or other fluid)therein for regulating a temperature of the body of vessel 312 duringmelting of material received in the vessel (e.g., to force cool thevessel). Such a forced-cool crucible can also be provided on the sameaxis as the plunger rod. The cooling channel(s) can assist in preventingexcessive heating and melting of the body of the vessel 312 itself.Cooling channel(s) may be connected to a cooling system configured toinduce flow of a gas or a liquid in the vessel. The cooling channel(s)may include one or more inlets and outlets for the fluid to flowthere-through. The inlets and outlets of the cooling channels may beconfigured in any number of ways and are not meant to be limited. Forexample, cooling channel(s) may be positioned relative to meltingportion 314 such that material thereon is melted and the vesseltemperature is regulated (i.e., heat is absorbed, and the vessel iscooled). The number, positioning and/or direction of the coolingchannel(s) should not be limited. The cooling liquid or fluid may beconfigured to flow through the cooling channel(s) during melting of themeltable material, when induction source 320L is powered.

After the material is melted in the vessel 312, plunger 330 may be usedto force the molten material from the vessel 312 and into a mold 340 formolding into an object, a part or a piece. In instances wherein themeltable material is an alloy, such as an amorphous alloy, the mold 340is configured to form a molded bulk amorphous alloy object, part, orpiece. Mold 340 has an inlet for receiving molten materialthere-through. An output of the vessel 312 and an inlet of the mold 340can be provided in-line and on a horizontal axis such that plunger rod330 is moved in a horizontal direction through body 22 of the vessel toeject molten material and into the mold 340 via its inlet.

As previously noted, systems such as injection molding system 300 thatare used to mold materials such as metals or alloys may implement avacuum when forcing molten material into a mold or die cavity. Injectionmolding system 300 can further includes at least one vacuum source orpump that is configured to apply vacuum pressure to at least melt zone310 and mold 340 at vacuum ports 312. The vacuum pressure may be appliedto at least the parts of the injection molding system 300 used to melt,move or transfer, and mold the material therein. For example, the vessel312, transfer sleeve 350, and plunger rod 330 may all be under vacuumpressure and/or enclosed in a vacuum chamber.

In an embodiment, mold 340 is a vacuum mold that is an enclosedstructure configured to regulate vacuum pressure therein when moldingmaterials. For example, in an embodiment, vacuum mold 340 includes afirst plate (also referred to as an “A” mold or “A” plate), a secondplate (also referred to as a “B” mold or “B” plate) positionedadjacently (respectively) with respect to each other. The first plateand second plate generally each have a mold cavity associated therewithfor molding melted material there-between. The cavities are configuredto mold molten material received there-between via an injection sleeveor transfer sleeve 350. The mold cavities may include a part cavity forforming and molding a part therein.

Generally, the first plate may be connected to transfer sleeve 350. Inaccordance with an embodiment, plunger rod 330 is configured to movemolten material from vessel 312, through a transfer sleeve 350, and intomold 340. Transfer sleeve 350 (sometimes referred to as a shot sleeve, acold sleeve or an injection sleeve in the art and herein) may beprovided between melt zone 310 and mold 340. Transfer sleeve 350 has anopening that is configured to receive and allow transfer of the moltenmaterial there-through and into mold 340 (using plunger 330). Itsopening may be provided in a horizontal direction along the horizontalaxis (e.g., X axis). The transfer sleeve need not be a cold chamber. Inan embodiment, at least plunger rod 330, vessel 312 (e.g., its receivingor melting portion), and opening of the transfer sleeve 350 are providedin-line and on a horizontal axis, such that plunger rod 330 can be movedin a horizontal direction through vessel 312 in order to move the moltenmaterial into (and subsequently through) the opening of transfer sleeve350.

Molten material is pushed in a horizontal direction through transfersleeve 350 and into the mold cavity(ies) via the inlet (e.g., in a firstplate) and between the first and second plates. During molding of thematerial, the at least first and second plates are configured tosubstantially eliminate exposure of the material (e.g., amorphous alloy)there-between, e.g., to oxygen and nitrogen. Specifically, a vacuum isapplied such that atmospheric air is substantially eliminated fromwithin the plates and their cavities. A vacuum pressure is applied to aninside of vacuum mold 340 using at least one vacuum source that isconnected via vacuum lines 332. For example, the vacuum pressure orlevel on the system can be held between 1×10⁻¹ to 1×10⁻⁴ Torr during themelting and subsequent molding cycle. In another embodiment, the vacuumlevel is maintained between 1×10⁻² to about 1×10⁻⁴ Torr during themelting and molding process. Of course, other pressure levels or rangesmay be used, such as 1×10⁻⁹ Torr to about 1×10⁻³ Torr, and/or 1×10⁻³Torr to about 0.1 Torr. An ejector mechanism (not shown) is configuredto eject molded (amorphous alloy) material (or the molded part) from themold cavity between the first and second plates of mold 340. Theejection mechanism is associated with or connected to an actuationmechanism (not shown) that is configured to be actuated in order toeject the molded material or part (e.g., after first and second partsand are moved horizontally and relatively away from each other, aftervacuum pressure between at least the plates is released).

Any number or types of molds may be employed in the apparatus 300. Forexample, any number of plates may be provided between and/or adjacentthe first and second plates to form the mold. Molds known in the art as“A” series, “B” series, and/or “X” series molds, for example, may beimplemented in injection molding system/apparatus 300.

A uniform heating of the material to be melted and maintenance oftemperature of molten material in such an injection molding apparatus300 assists in forming a uniform molded part. For explanatory purposesonly, throughout this disclosure material to be melted is described andillustrated as being in the form of an ingot 305 that is in the form ofa solid state feedstock; however, it should be noted that the materialto be melted may be received in the injection molding system orapparatus 300 in a solid state, a semi-solid state, a slurry that ispreheated, powder, pellets, etc., and that the form of the material isnot limiting. In addition, the illustrated view of vessel 312 is across-sectional view taken along X-axis of a U-shaped boat/vessel forillustrative purposes only.

In an injection molding apparatus that is positioned inline and in ahorizontal direction and to get the most power input into the materialfor melting, containing the material in the melt zone, adjacent toinduction coil, is effective for a consistent melt cycle, rather than,for example, having molten material flow towards and/or out of theejection path of the vessel.

FIG. 4 depicts a current injection molding system configured having oneinduction coil 420. The coil 420 may impose forces on the material 405for melting, e.g., metals/metal alloys, placed inside the vessel 410,and ultimately, when the material 405 is molten, the induction coil 420imposes forces on the molten material 405 within the coil 420. Theseforces may act to squeeze the molten material inwards to the center ofthe vessel, as shown. Meanwhile, these forces may push the moltenmaterial 405 out of the induction coil 420 e.g., at the ends of theinduction coil 420, while the molten material is being smoothed outduring heating by the induction coil.

As disclosed herein, the exemplary injection molding apparatus/system300 in FIG. 3 includes a plurality of separate induction coils, such as,for example, a load induction coil 320L and a containment induction coil320C.

In embodiments, the induction coils 320L and 320C can emitradiofrequency (RF) waves towards the vessel 312. The coils 320L and320C may or may not be tapered. The coils 320L and 320C may include,e.g., spherical coil. In embodiments, the coils may have the same ordifferent shapes such that the generated RF fields can be tuned, e.g.,be more directional as desired. For example, the containment inductioncoil 320C can be taper-shaped or cone-shaped coil, with the wide regionspacing from, facing, the load induction coil 320L. By using the tunedRF fields, stronger forces can be generated by the containment inductioncoil 320C and imposed to the melt toward the load induction coil 320L.The melt/molten material can then be contained within the load inductioncoil 320L.

The containment induction coil 320C can be spaced apart but configuredin line with the load induction coil 320L. The containment inductioncoil 320C can be configured near the ejection end of the melting zone310. The load induction coil 320L can be configured for heating/meltingthe material 305 for melting placed in the melting portion 314 of thevessel 310. The containment induction coil 320C can be configured forpositioning and/or containing the melt or molten material within theload induction coil 320L during the heating/melting process. Thecontainment induction coil 320C can prevent the melt or the moltenmaterial from flowing out of the load induction coil 320L and thematerial 305 in the vessel 312 can remain heated and molten. Likewise,the melt/molten material can be contained within the melt zone 310 ofthe apparatus/system 300 while it's being smoothed out and minimize heatloss.

In embodiments, the containment induction coil 320C and the loadinduction coil 320L can be operated at different frequencies in order toposition/contain the melt, e.g., at melting temperatures. For example,the load induction coil 320L for heating/melting the meltable materialscan operate at one frequency f_(melting), while the containmentinduction coil 320C for containing the melt/molten material can operateat a different frequency f_(containment). In embodiments, f_(melting),may be greater than f_(containment). The containment induction coil 320Coperating at a lower frequency may generate a stronger net force on themelt/molten material. The containment induction coil 320C may imposesuch force, e.g., Laplace forces, on the melt, to act against thosegenerated by the load induction coil (which tend to push the melt out)and push the melt back to be contained within the load induction coil320L.

The containment induction coil 320C and the load induction coil 320L arespaced apart and operated out of sync in frequencies. The magneticfields generated by the coils 320C and 320L do not necessarily cancelout (although they may otherwise interact) with one another. In general,when two coils have coil turns, e.g., helical turns, in reversed oropposite directions, the magnetic fields generated may oppose to andcancel out with one another. In such region where the opposing turns arein effect, the materials to be melted cannot be heated and may tend tofreeze onto the vessel due to cancellation of the magnetic fields.

As disclosed herein, by controlling frequencies, powers, interactionbetween magnetic fields, etc. of one or both of the load induction coil320C and the containment induction coil 320, the materials 305 in thevessel 312 can be heated/melted and further contained within the loadinduction coil 320C.

In embodiments, the containment induction coil 320 c can be energized orde-energized as needed to function as a gate or a valve in the ejectionpath of the melt from the vessel 312 to the mold 340 and/or to controlmovement of the melt in the ejection path into the mold 340. Forexample, when the material 305 is heated/melted by operating the loadinduction coil 320L, by turning on the containment induction coil 320Cthe heated material/melt can be contained within the load induction coil320L; by turning off the containment induction coil 320C, the melt canbe ejected from or pushed out of the load induction coil 320L; and/or byturning the containment induction coil 320C back on, e.g., as a portionof the melt passed the “gate region” or the ejection end of the vessel312, this portion of the melt can keep moving through the transfersleeve (e.g., a cold sleeve or a shot sleeve) of the mold 340, while themelt portion within the load induction coil 320L can be contained.

In this manner, the vessel 312 is positioned along a horizontal axis(X-axis) such that the movement of the molten material/melt can be in ahorizontal direction when directed through the ejection path (e.g.,using plunger 330). Surrounding at least part of vessel 312 is loadinduction coil 320L, and surrounding at least part of the vessel 312near the ejection end of the vessel 312 is the containment inductioncoil 320C, such that materials are heated/melted by the load inductioncoil 320L and contained within the load induction coil 320L.

In embodiments, as shown in FIG. 5, a second containment induction coil320C2 can be configured in line with the load induction coil 320L at anopposite end of the containment induction coil 320C1, i.e., at anopposite side of the injection path. The first and second containmentinduction coil 320C1-C2 may be the same or different and may becontrolled to have the same or different functions. In this manner, themelt 305 in the vessel 312 can be contained within the load inductioncoil 320L from both ends thereof.

In embodiments, when utilizing BMG as the material in the injectionmolding apparatus 300/500, articles/parts with a high elastic limit,corrosion resistance, and low density can be formed.

FIG. 6 illustrates a method 600 for melting material and/or molding apart in accordance with an embodiment of the disclosure using apparatus300 and/or 500, as shown in FIGS. 3 and 5, although the apparatus andmethods disclosed herein are not limiting with one another in anymanner.

At block 610 of FIG. 6, an apparatus is designed to include, forexample, a vessel 312 configured to receive a material 305 for meltingtherein, a load induction coil 320L positioned adjacent the vessel tomelt the material 305 therein; and a containment induction coil 320Cpositioned in line with the load induction coil. Generally, theinjection molding apparatus 300/500 may be operated in the followingmanner: materials for melting 305 (e.g., amorphous alloy or BMG in theform of a single ingot) can be loaded into a feed mechanism (e.g.,loading port 318), inserted and received into the melt zone 310 into thevessel 312 (surrounded by the load induction coil 320L). The injectionmolding machine “nozzle” stroke or plunger 330 can be used to move thematerial, as needed, into the melting portion 314 of the vessel 312.

At block 620, the material 305 for melting can be heated through theinduction process, e.g., by supplying power via a power source 325L tothe load induction coil 320L. During heating/melting, a cooling systemcan be activated to flow a (cooling) fluid in any cooling channel(s) 316of the vessel 312. The injection molding machine controls thetemperature through a closed or opened loop system, which will stabilizethe material 305 at a specific temperature (e.g., using a temperaturesensor and a controller).

At block 630, the containment induction coil 320C can be operated at aRF frequency lower than the load induction coil 320L to control theposition and shape of the molten material or molten feedstock in theinline melting apparatus. The containment induction coil 320C may exerta force, e.g., Laplace forces, on the molten material, acting againstthose generated by the load induction coil (which tends to push themolten material out) without substantially reducing the inductiveheating of the molten material 305.

At block 640, once the desired temperature is achieved and maintainedfor the melt in the vessel 312, the ejection path of the vessel 312 canbe “opened” by turning off the containment induction coil 320C such thatthe melt/molten material can be subsequently ejected from the vesselinto a mold 340 through an ejection path, e.g., the transfer sleeve 350,e.g., as seen at block 650 of FIG. 6. The mold 340 can be any mold in acaster such as a cold chamber die. The ejection can be performed in ahorizontal direction (e.g., from right to left as shown in FIGS. 3 and5) along the horizontal axis (X axis). This may be controlled usingplunger 330, which can be activated, e.g., using a servo-driven drive ora hydraulic drive. The mold 340 is configured to receive molten materialthrough an inlet and configured to mold the molten material undervacuum, for example. That is, the molten material is injected into anevacuated cavity between the at least first and second plates to moldthe part in the mold 340. As previously noted, in some embodiments, thematerial may be an amorphous alloy material that is used to mold a bulkamorphous alloy part. Once the mold cavity has begun to fill, pressure(via the plunger) can be held at a given level to “pack” the moltenmaterial into the remaining void regions within the mold cavity and moldthe material. After the molding process (e.g., approximately 10 to 15seconds), the vacuum applied to at least the mold 340 (if not the entireapparatus 300/500) can be released. Mold 340 is then opened and thesolidified part is exposed to the atmosphere. In embodiments, an ejectormechanism is actuated to eject the solidified, molded object frombetween the at least first and second plates of mold 340 via anactuation device (not shown). Thereafter, the process can begin again.Mold 340 can then be closed by moving at least the at least first andsecond plates relative to and towards each other such that the first andsecond plates are adjacent each other. The melt zone 310 and mold 340 isevacuated via the vacuum source once the plunger 330 has moved back intoa load position, in order to insert and melt more material and moldanother part.

Although not described in great detail, the disclosed injection systemmay include additional parts including, but not limited to, one or moresensors, flow meters, etc. (e.g., to monitor temperature, cooling waterflow, etc.), and/or one or more controllers. The material to be molded(and/or melted) using any of the embodiments of the injection system asdisclosed herein may include any number of materials and should not belimited. In one embodiment, the material to be molded is an amorphousalloy, as described above.

Applications of Embodiments

The presently described apparatus and methods can be used to formvarious parts or articles, which can be used, for example, for Yankeedryer rolls; automotive and diesel engine piston rings; pump componentssuch as shafts, sleeves, seals, impellers, casing areas, plungers;Wankel engine components such as housing, end plate; and machineelements such as cylinder liners, pistons, valve stems and hydraulicrams. In embodiments, apparatus and methods can be used to form housingsor other parts of an electronic device, such as, for example, a part ofthe housing or casing of the device or an electrical interconnectorthereof. The apparatus and methods can also be used to manufactureportions of any consumer electronic device, such as cell phones, desktopcomputers, laptop computers, and/or portable music players. As usedherein, an “electronic device” can refer to any electronic device, suchas consumer electronic device. For example, it can be a telephone, suchas a cell phone, and/or a land-line phone, or any communication device,such as a smart phone, including, for example an iPhone™, and anelectronic email sending/receiving device. It can be a part of adisplay, such as a digital display, a TV monitor, an electronic-bookreader, a portable web-browser (e.g., iPad™), and a computer monitor. Itcan also be an entertainment device, including a portable DVD player,DVD player, Blu-Ray disk player, video game console, music player, suchas a portable music player (e.g., iPod™), etc. It can also be a part ofa device that provides control, such as controlling the streaming ofimages, videos, sounds (e.g., Apple TV™), or it can be a remote controlfor an electronic device. It can be a part of a computer or itsaccessories, such as the hard driver tower housing or casing, laptophousing, laptop keyboard, laptop track pad, desktop keyboard, mouse, andspeaker. The coating can also be applied to a device such as a watch ora clock.

While the invention is described and illustrated here in the context ofa limited number of embodiments, the invention may be embodied in manyforms without departing from the spirit of the essential characteristicsof the invention. The illustrated and described embodiments, includingwhat is described in the abstract of the disclosure, are therefore to beconsidered in all respects as illustrative and not restrictive. Thescope of the invention is indicated by the appended claims rather thanby the foregoing description, and all changes that come within themeaning and range of equivalency of the claims are intended to beembraced therein.

What is claimed is:
 1. A method comprising: placing a material in ahorizontally oriented vessel; operating a first induction coilcomprising a plurality of coil turns at least partially surrounding thevessel and defining a melt zone at a first RF frequency, thereby forminga molten material; while operating the first induction coil, operating asecond induction coil at least partially surrounding the vessel andpositioned in line with the first induction coil at a second RFfrequency that is different that the first RF frequency to contain thematerial within the melt zone; and forming the molten material into abulk metallic glass (BMG) part.
 2. The method of claim 1, wherein thesecond RF frequency is lower than the first RF frequency.
 3. The methodof claim 1, further comprising, while operating the first inductioncoil, operating an additional induction coil positioned in line with thefirst induction coil and at an end of the vessel opposite the secondinduction coil at a third RF frequency that is different than the firstRF frequency to contain the material within the melt zone.
 4. The methodof claim 3, wherein the third RF frequency is lower than the first RFfrequency.
 5. The method of claim 1, wherein: the vessel comprises oneor more temperature regulating channels; and the method furthercomprises regulating a temperature of the vessel while operating thefirst induction coil by flowing a fluid through the one or moretemperature regulating channels.
 6. The method of claim 1, furthercomprising: stopping operation of the second induction coil; andejecting the molten material from the vessel into a mold to mold the BMGpart.
 7. The method of claim 6, wherein: the vessel is configured toreceive at least part of a plunger there-through; and the operation ofejecting the molten material from the vessel into the mold comprisesejecting the molten material with the plunger.
 8. The method of claim 1,further comprising containing the material within the melt zone withoutusing a physical barrier along an ejection path of the vessel to containthe material.
 9. The method of claim 1, wherein: the material comprisesa BMG feedstock; and the first induction coil is not physicallyconnected to the second induction coil.
 10. The method of claim 1,wherein: the material comprises a BMG feedstock; and the first inductioncoil and the second induction coil are connected as a single inductioncoil structure comprising an electrical tap; and the first inductioncoil and the second induction coil are independently controlled via theelectrical tap.
 11. The method of claim 1, wherein: operating the firstinduction coil imparts a first force on the material tending to ejectthe material from the melt zone; and operating the second induction coilimparts a second force on the material in a direction substantiallyopposite the first force.
 12. A method of operating an apparatus,comprising: operating a first induction coil at a first RF frequency toform a molten material in a horizontally oriented vessel; whileoperating the first induction coil, operating a second induction coil ata second RF frequency to contain the molten material within a melt zonedefined by the first induction coil without using a physical barrieralong an ejection path of the vessel, the second RF frequency beingdifferent from the first RF frequency; and ejecting the molten materialfrom the horizontally oriented vessel and into a mold.
 13. The method ofclaim 12, wherein the method is performed under vacuum by applying avacuum to at least the mold from a vacuum source.
 14. The method ofclaim 12, wherein the first induction coil at least partially surroundsthe second induction coil.
 15. A method comprising: placing a materialin a horizontally oriented vessel; powering a first induction coilcomprising a plurality of coil turns at least partially surrounding thevessel, thereby forming a molten material; while powering the firstinduction coil, powering a second induction coil at least partiallysurrounding the vessel to contain the material within an area surroundedby the first induction coil, the first and the second induction coilbeing powered so that a frequency of operation of the first coil is notsynchronized with a frequency of operation of the second coil; andmolding the molten material into a bulk metallic glass (BMG) part. 16.The method of claim 15, further comprising ejecting the molten materialfrom the vessel and into a mold cavity to mold the molten material intothe BMG part.
 17. The method of claim 15, wherein the second inductioncoil is positioned in line with the first induction coil.
 18. The methodof claim 17, wherein the second induction coil is spaced apart from thefirst induction coil.
 19. The method of claim 15, wherein: the areasurrounded by the first induction coil defines a melt zone; powering thefirst induction coil imparts a first force on the material tending toeject the material from the melt zone; and powering the second inductioncoil imparts a second force on the material in a direction substantiallyopposite the first force.
 20. The method of claim 15, wherein the secondinduction coil is at least partially surrounded by the first inductioncoil.